Speaker
Description
We numerically study the non-perturbative renormalization group flow of general quadratic gravity, using the flow equations derived by Sen, Wetterich and Yamada, with boundary conditions consistent with the Hubble scale, laboratory tests of gravity and Starobinsky inflation. By a slight shift of the infrared reference scale, we obtain trajectories that avoid the infrared singular behavior near the Hubble scale. We find two types of trajectories: one approaches the Reuter fixed point (asymptotically safe gravity), while the other flows to a regime effectively described by the R^2+C^2 action near the Planck scale. Whether a trajectory consistent with all observations can reach the asymptotically free regime remains open. This talk is based on Phys. Rev. D 106, 086024 (2022) [arXiv:2207.11399] and a forthcoming paper.